Apparatus for detecting the position of a movable article under water

ABSTRACT

An apparatus for detecting the position of a movable article under water which has at least three ultrasonic receivers equidistantly spaced around a standard point provided on the bottom of the body of water, an ultrasonic transmitter mounted onto the movable article for transmitting pulse ultrasonic waves, means for measuring the difference in the time when the receiver initially receives the ultrasonic wave and the time when the respective receivers receive the ultrasonic wave, and means for calculating the position of the movable article from the receiver initially receiving the ultrasonic wave and the standard point as a standard from the measured result of the measuring means. Thus, the apparatus of this invention may measure the position of the movable article under water regardless of the affect of the reflection of the ultrasonic wave from the rock, etc. on the bottom of the sea.

United States Patent [191 Nakatsuji et al.

[451 Feb. 12,1974

[ APPARATUS FOR DETECTING THE POSITION OF A MOVABLE ARTICLE UNDER WATER[75] Inventors: Shinichi Nakatsuji, Chigasaki-shi;

Keisuke Suzuki, l-Iiratsuka-shi, both of Japan [73] Assignee: KabushikiKaisha Komatsu Seisakusho, Tokyo, Japan [22] Filed: Oct. 13, I971 [21]Appl. No.: 188,859

[30] Foreign Application Priority Data Oct. 13, I970 Japan 45-89291 [57]ABSTRACT An apparatus for detecting the position of a movable articleunder water which has at least three ultrasonic receivers equidistantlyspaced around a standard point provided on the bottom of the body ofwater, an ultrasonic transmitter mounted onto the movable article fortransmitting pulse ultrasonic waves, means for measuring the differencein the time when the receiver initially receives the ultrasonic wave andthe time when the respective receivers receive the ultrasonic wave, andmeans for calculating the position of the movable article from thereceiver initially receiving the ultrasonic wave and the standard pointas a standard from the measured result of the measuring means. Thus, theapparatus of this invention may measure the position of the movablearticle under water regardless of the affect of the reflection of theultrasonic wave from the rock, etc. on the bottom of the 4 Claims, 7Drawing Figures [52] U.S. Cl. 340/6 R [51] Int. Cl. G01s 5/18 [58] Fieldof Search 340/5 R, 6 R, 16 R, 1 C

[56] References Cited UNITED STATES PATENTS 3,421,138 l/l969 Moulin etal 340/5 R Sm 3,205,475 9/1965 Foss 340/6 R 3,161,255 12/1964 Balise,Jr. 340/8 S |5b l lb l l C 6 l0 l5c I50 PATENTEUFEBIZW 5.792.424

SHEUIUFZ TRANSMITTER I lTc MEASURER PAIENTEU run 2197;

sum 2 or 2 FIG.

IIC

APPARATUS FOR DETECTING THE POSITION OF A MOVABLE ARTICLE UNDER WATERThis invention relates to an apparatus for detecting the position of amovable article under water utilizing an ultrasonic wave.

The development of oceans for putting the resources on the bottom of thesea to practical use has recently grow prosperous. When such developmentof the bottom of the sea is conducted, it is often required that anunder-water service car or vehicle be operated beneath the surface inorder to work under water. In such case, it is necessary to accuratelyknow the position of the service car under water so as to permit smoothoperation and to eliminate under sea dangers. This is particularlyimportant in the event that the under-water service vehicle is driven bya remote control without a human operator.

I-Ieretofore, for example, has been known a device which has a PPIsonar, five transponders (one of which is mounted onto the under-waterservice car), wherein an ultrasonic wave is transmitted from the PP]sonar and is received by the transponders and is returned to the PHsonar for indicating the position of the service car on a cathod raytube for the detection of the movable article or under-water service carbeneath the water. However, in such method, an echo is reflected fromprojections such as rocks existing around the underwater service car onthe bottom of the sea. As a result,

it is very difficult to discriminate between the projections and theunder-water service car, and accordingly the conventional device has adisadvantage such that it is impossible to accurately measure theposition of the service car under water.

This invention contemplates the elimination of the aforementioneddisadvantages of the conventional device and has as an object theprovision of an apparatus for detecting the position of a movablearticle under water which may positively measure the position of themovable article under water without being affected by the echo of rocks,etc. on the bottom of the sea.

Briefly, in accordance with this invention, the foregoing and otherobjects, features and advantages are attained by the provision of anapparatus for detecting the position of a movable article under waterwhich comprises at least three ultrasonic receivers equidistantlydisposed around a standard point provided on the bottom of the body ofwater, an ultrasonic transmitter mounted onto the movable article fortransmitting pulse ultrasonic waves, means for measuring the differenceof the time when the receiver initially receives the ultrasonic wave andthe time when the respective receivers recive the ultrasonic wave, andmeans for calculating the position of the movable article from thereceiver initially. receives the ultrasonic wave and the standard pointas a standard from the measured result of the measuring means.

A more complete appreciation of the invention will be readily obtainedasv the same becomes better understood by reference to the followingdetailed description when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a schematic view of overall arrangement of the apparatus ofthis invention;

FIG. 2 is a block diagram of the transmitter of the apparatus of thisinvention;

FIG. 3 is a block diagram of the receiver of the apparatus of thisinvention;

FIG. 4 is a block diagram of the measuring portion of the apparatus ofthis invention;

FIG. 5 is a graphical representation of the relationship of the relativeposition of the transmitter and receivers of this invention;

FIG. 6 is a graphical representation of the timing relations of thetrigger pulse, transmitting pulse and received pulses of the apparatusof this invention; and

FIG. 7 is a block diagram of another example of the measuring portion ofthe apparatus of this invention.

Reference is now made to the drawings, which show one embodiment of theapparatus for detecting the position of a movable article under water ofthis invention.

In FIG. 1, which shows the overall arrangement of the apparatus of thisinvention, a measuring ship 1 is floated on the sea. A controller 2 andmeans for measuring the position of a movable article under water, suchas measuring equipment 3, are provided in this ship. On the top ofanunder-water service car 4 disposed on the bottom of the sea is mountedan ultrasonic transmitter 5. An ultrasonic receiver 6 is disposed at thestandard point 0 predetermined on the bottom of the sea. Then,respective trigger pulses TR of constant period are transmitted from thecontroller 2 through the transmitter 5 so as to energize the pulseoscillator 8 of the transmitter 5 with the trigger pulses TR tooscillate transmitting pulses RP synchronized with the period of thetrigger pulses. The pulses are then amplified by a power amplifier 9,and are supplied to a transmitter 10 from which pulse ultrasonic wavesare transmitted through the water. The ultrasonic waves thus transmittedare received by three receivers 1 la, 11b and llc of the receiver 6 inwhich the received ultrasonic pulses Sa, Sb and Sc are amplified by therespective amplifiers 12a, 12b and 120 to be transmitted to themeasuring equipment 3 through a cable 13. The ultrasonic receiver 6 isso constructed that a post 14 is erected at the standard point 0, threebranches 15a, 15b and 15c are equidistantly projected radially inhorizontal direction in space of 120 therebetween around the post 14 andthe receivers 11a, 11b and are mounted to the free ends of therespective branches 15a, 15b 156.

As shown in FIG. 5, which shows the relationship of the relativeposition of the transmitter and receivers of this invention, since thereceivers 11a, 11b and 110 are so disposed equidistantly with a space oftherebetween on a circular periphery around the standard point 0 as acenter at a distance of R from the transmitter 10, the distance Ra, Rband Re of the respective receivers 11a, 1 1b and 11c with respect of thetransmitter 10 are different from each other. Therefore, assuming thatthe relationship of the distances Ra, Rb and Re is Ra Rb Rc, as shown inFIG. 6, which shows the timing relation of the trigger pulses, thetransmitting pulse and received pulse of the apparatus of thisinvention, an initial received pulse S is generated at the receiver 11aafter the time of 1' from the generation of the trigger pulse signal.Thereafter, the second received pulse S is generated at the receiver 11bafter the time of t and then the third received pulse 8;, is generatedat the receiver 11c after the time of t Assume that the distance R ofthe transmitter and receivers is now sufficiently large in comparisonwith the wavelength of the pulsing wave, the ultrasonic wave reaches thereceivers as a plane wave, and accordingly assuming that C representsthe velocity of sound (m/sec.), r represents the distances (m) betweenthe standard point and the respective receivers 11a, 11b and 11c, thetimes t and t may be obtained by the following formulae. It is assumedthat the transmitter 10 is disposed at the position in the direction of01 with respect to the direction of the receiver Sb from the straightline for connecting the receiver 11a and the standard point 0.

t, 3r cosa \/3 r sina/ZC t 3r cosa 3 r sina/2C wherein C and r areconstants, and if the times t and 1 are measured, the angle of a may beobtained, and if the time T from when the transmitting pulse isgenerated to when initial received pulse 8, is generated is multipliedby the constant C, the distance R may be obtained.

And, the components X and Y of the position of the underwater servicecar 4 may be obtained from the following formulae:

Y R-cu i,/ 5 r) In this embodiment of the apparatus of this invention,the receiver pulse is fed to the measuring equipment 3, by which therespective received pulse from the receivers 11a, 11b and lie aremeasured in the generating order thereof so as to discriminate the areawhere the transmitter is disposed, and by which the times 1', t and tare measured and the position of the transmitter 10, i.e., the positionof the under-water service car 4 is calculated by calculating means, andis indicated by X-Y recorder, oscilloscope, etc. More particularly, themeasuring equipment 3 supplies the trigger pulse signal from thecontroller 2 to gates 16a, 16b and 160 so as to open the gates tooperate the following counters 17a, 17b and 17c, respectively. Then, themeasuring equipment 3 feeds the received pulses Sa, Sb and Sc from thereceivers 11a, 11b and 110 to an area discriminating circuit 18simultaneously to the gates 16a. 16b and 160 so as to close the gates tostop the operation of the counters 17a, 17b and 170.

Thus, since the respective counters 17a, 17b and 170 operate to countfrom when they are energized by the triggers to when they aredeenergized by the received pulses so as to measure the time from whenthe triggers or transmitted pulses are generated to when the respectivereceived pulses are generated. The measured outputs from the measuringequipment 3 are then converted to analog value by D-A converters 19a,19b and 190, respectively, and are then supplied to arithmetic circuit20. On the other hand, the area discriminating circuit 18 operates todiscriminate the area where the transmitter, i.e., the under-waterservice car 4 is disposed from the received pulses Sa, Sb and Sc in thegenerating order so as to supply the discriminated output to thearithmetic circuit 20. The arithmetic circuit 20 calculates the positionof the service car 4 from the outputs of the measuring equipment 3 andthe outputs of the area discriminating circuit 18 to provide the outputsof X and Y components of the position of the service car 4.

Then, these outputs of X and Y components of the position of the servicecar 4 from the arithmetic circuit 20 are applied to display unit such asthe X-Y recorder, or a oscilloscope to indicate the position of theservice car 4.

The following formula is obtained from the formula (3):

From this formula as shown in FIG. 7, which shows another embodiment ofthe measuring equipment of the apparatus of this invention, the signalobtained by the above formula is supplied through a servo amplifier 21to a servo motor 22 which rotates a resolver 23. Thus, using therotating angle of this resolver 23 as a table signal of a recorder forindicating a polar coordinates and the distant signal R obtained aspreviously described, the position of the underwater service car 4 maybe indicated.

In the aforementioned embodiment, though the outputs of the counters arefed through D-A converters to the arithmetic circuit, it may obtain thesame effect by applying the outputs of the counters directly to thearithmetic circuit so as to calculate them in digital computation andthen by converting the results thus obtained to analog value such asvoltage by a D-A converter.

It should be understood from the foregoing description that since theapparatus of this application calculates the position of the movablearticle under water from the time difference of the time when thereceivers initially receive the supersonic waves transmitted by thetransmitter and the time when the respective receivers receive thesupersonic waves, even through there exists echo reflected on the rockson the bottom of the sea, the measurement and calculation of theposition of the movable article under water are not affected by the echobecause the echo is delayed in time with the result that the apparatusmay detect the accurate position of the movable article under water.

What is claimed is:

1. An apparatus for detecting the position of a movable article underwater comprising at least three ultrasonic receivers equidistantlydisposed around a standard point provided at the bottom of a body ofwater and so disposed as to sequentially receive any transmitted signal,an ultrasonic transmitter mounted onto the movable article fortransmitting ultrasonic pulse waves, means for measuring the differencein the time when any receiver initially receives the ultrasonic wave andthe time when the respective additional receivers sequentially receivethe ultrasonic wave, and means for calculating the position of themovable article relative to the receiver initially receiving theultrasonic wave with reference to a standard point as a standard fromthe measured result of said measuring means can be compared and whereinsaid receivers comprise a post located at the standard point, aplurality of branches they receive the signal from said controller, anarea discriminating circuit for closing said gates when it receives thethe pulse from the receivers, and a plurality of counters for countingthe time from when said receivers are energized to when they aredeenergized by the pulses.

3. An apparatus as set forth in claim 1, wherein said calculating meanscomprises an arithmetic circuit for calculating the position of themovable article under water from the output of said measuring means toprovide X and Y components of the position of the movable article.

4. An apparatus as set forth in claim 1, wherein said calculating meanscomprises an arithmetic circuit for calculating the angular position anddistant position of the movable article under water from the outputs ofsaid measuring means to provide the 'r and R components of the positionof the movable article for indicating polar coordinates.

1. An apparatus for detecting the position of a movable article underwater comprising at least three ultrasonic receivers equidistantlydisposed around a standard point provided at the bottom of a body ofwater and so disposed as to sequentially receive any transmitted signal,an ultrasonic transmitter mounted onto the movable article fortransmitting ultrasonic pulse waves, means for measuring the differencein the time when any receiver initially receives the ultrasonic wave andthe time when the respective additional receivers sequentially receivethe ultrasonic wave, and means for calculating the position of themovable article relative to the receiver initially receiving theultrasonic wave with reference to a standard point as a standard fromthe measured result of said measuring means can be compared and whereinsaid receivers comprise a post located at the standard point, aplurality of branches equidistantly projected radially in horizontaldirection in space of 120 degrees distance therebetween around the postand a plurality of individual ultrasonic receivers mounted on the freeends of the respective branches.
 2. An apparatus as set forth in claim1, wherein said measuring means comprises a controller for generating atrigger pulse, a plurality of gates which open when they receive thesignal from said controller, an area discriminating circuit for closingsaid gates when it receives the the pulse from the receivers, and aplurality of counters for counting the time from when said receivers areenergized to when they are deenergized by the pulses.
 3. An apparatus asset forth in claim 1, wherein said calculating means comprises anarithmetic circuit for calculating the position of the movable articleunder water From the output of said measuring means to provide X and Ycomponents of the position of the movable article.
 4. An apparatus asset forth in claim 1, wherein said calculating means comprises anarithmetic circuit for calculating the angular position and distantposition of the movable article under water from the outputs of saidmeasuring means to provide the Tau and R components of the position ofthe movable article for indicating polar coordinates.